This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from my application entitled Ink-Jet Printer With Function of Preventing Jamming Caused by Paper Warping filed with the Korean Industrial Property office on Jan. 6, 1997 and there duly assigned Ser. No. 97-00105 by that Office.
1. Field of the Invention
The present invention relates to printers and, more particularly, to a device for preventing the jamming of printed sheets of paper that become curled during conveyance.
2. Discussion of Related Art
A typical ink-jet printer is generally includes a paper feeding device for supplying paper in sheets, a conveying device for conveying the supplied paper from the paper feeding device, a printing device for performing a print operation on the conveyed paper, and a discharging device for discharging printed paper. FIG. 1 shows the internal construction of such a printer.
In FIG. 1, sheets of paper 1 are seated on a paper feeding device 10 and individually fed through a conveying device 20 by a plurality of feed rollers 21 and friction rollers 22. A printing device 30 is provided with a pulley 32 driven by a motor 31 via a timing belt 33, which laterally transfers a carriage 34 that carries of print heads 35. Line-by line printing is performed as the heads 35 move left and right across the paper that is gradually conveyed over a base frame 40 toward a discharging device 50. The base frame 40 acts as a support plate for printing in opposition to the reciprocating print heads 35. When the paper bearing formed images arrives at the discharging device 50, it is discharged between a plurality of discharging rollers 52, being rotated by force transmission rollers 51 that are in contact with the feed rollers 21, and a plurality of star wheels 53 (shown in FIG. 2). A cover door 60 is installed on the ink-jet printer.
Accordingly, the paper path consists of the paper feeding device, the conveying and printing device, and the discharging device. It should be appreciated that, in such an ink-jet printer, the leading edge of the paper being carried from the conveying device to the discharging device is not constrained and is thus free to curl or become distorted in shape (flatness). This is especially true of in dry environment conditions.
As shown in FIG. 2, as the curled sheet of paper 1 moves over the base frame 40 without means for constraint, the leading edge thereof cannot be smoothly inserted between the star wheel 53 and discharging roller 52 and thus escapes from the conveyance path, resulting in a paper jam. Though this problem is particularly exacerbating in a dry environment, any similar warping curling of the printing paper, either before or during printing, tends to cause similar paper jamming conditions.
Therefore, in order to overcome such drawbacks of the prior art, an objective of the present invention is to provide a device which prevents paper jamming, even if the leading edge of a conveyed sheet of paper printed is curled.
It is another objective of the present invention to provide an ink-jet printer whose structure provides for paper jamming prevention means without undue increases in product costs.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided a paper jamming prevention device having: a conveying portion for conveying a sheet of paper from a paper feeding portion according to a feed command; a discharging portion for receiving the conveyed sheet of paper for discharge; and a base frame, installed between the conveying portion and the discharging portion, having a flat surface disposed toward the conveying portion. The conveying portion located toward the discharging portion, is curved and induces the paper to sag.
In the preferred embodiment of the present invention, the base frame over which printed paper is conveyed has a curved conveyance surface, excluding a printing surface of which must be flat, along which discharging means are disposed. As a printed sheet of paper passes through the curved conveyance surface of the base frame, it is inherently contoured such that the cross-section of the paper""s middle region is depressed. Therefore, even with an upward warping force, the leading edge of the paper retains its directness of forward orientation and does not curl upward, due to the inherent rigidity maintained by the sagging of the middle region thereof.